The use of a flexible membrane structure as a seal for various pump and pressure operated systems can be found in a variety of applications in the art. For example, U.S. Pat. No. 4,181,477, which issued to K. Litt on Jan. 1, 1980, discloses a pump valve incorporating a flexible valve seat connected to a reciprocating pumping piston, wherein such valve seat moves with the piston and isolates the pumped media from the exterior piston surface. The Litt valve seat deforms and stretches to permit reciprocation of the pumping piston while maintaining a peripheral seal thereabout. The flexibility and memory of the valve seat material allow it to return to its original shape between deformations. Similarly, U.S. Pat. No. 4,310,107, which issued to W. Wesner on Jan. 12, 1982, illustrates a manually operated trigger-type pump dispenser incorporating a flexible elastomeric diaphragm-like cover on one side of its internal pump chamber. The Wesner diaphragm-like cover is operatively associated with the trigger device such that, upon actuation of such device, it flexes and stresses in a direction to decrease the chamber volume. Upon release of the trigger actuation force, the diaphragm returns to its original condition as a result of elastic memory. Another flexible seal is disclosed in U.S. Pat. No. 2,360,603, which issued to L. Ward on Oct. 17, 1944. The Ward reference describes an aerating bottle which includes a valve stem having a head portion embedded in a valve plug. The valve plug includes a flexible sleeve element made of resilient material which houses a spring which tends to normally seat the valve plug on a valve seat of the aerating bottle. When the valve plug is lifted from the valve seat, the sleeve element isolates the spring and valve plug interior from product being dispensed. When the valve is again closed, the sleeve element is thereby resiliently extended to its original condition by the force of the spring.
U.S. Pat. No. 1,296,391, which issued to L. Hirsch et al. on Mar. 4, 1919, describes a liquid dispenser incorporating a compressible bulb member which can be compressed to effectively pressurize the interior air space of the liquid dispenser to force contained liquid through the dispenser's outlet spout. The Hirsch et al. dispenser includes a plunger member having a lower portion which bears directly upon the outer surface of the compressible bulb to axially compress the same within the dispenser's spherical casing.
Additionally, rolling-type flexible diaphragms have been widely used in pneumatic-type relay controls and other pump dispensing devices. For example, U.S. Pat. No. 4,219,042, which issued to W. St. Laurent, Jr. on Aug. 26, 1980, discloses a pneumatic relay incorporating a rolling diaphragm having an outer clamping flange and an inner clamping flange with an intermediate rolling wall. In particular, the St. Laurent, Jr. rolling diaphragm is immovably clamped about its periphery, and clamped at its center between a reciprocable valve seat and a compression spring retainer cup. As the valve seat is reciprocated axially within the relay, the rolling diaphragm walls serve to maintain a seal therewithin. Similarly, the Bellofram Corporation of Burlington, Mass. is a manufacturer of a variety of rolling diaphragms and describes many different models in its publication entitled Diaphragm Design Manual, published in 1980 by the Bellofram Corporation. Similar applications of rolling-type flexible diaphragms in pump dispensing applications are shown in U.S. Pat. Nos. 4,079,861 and 3,491,920, which issued to M. Brown on Mar. 21, 1978 and to F. Racki et al. on Jan. 27, 1970, respectively.
Despite the relatively wide use of such flexible and rolling-type diaphragm seals in pump dispensing applications, there remain problems of effectively attaching such diaphragms to reciprocable plunger structures in a manner which will not compromise the integrity of the diaphragm seal and which will provide smooth rolling of the rolling walls of such diaphragm without interference with adjacent structures. These problems become especially acute when such diaphragms are made of relatively thin materials which can be easily damaged and which are difficult to handle in the manufacturing process. Prior art structures did not adequately provide for easy manufacturing and handling of such thin-walled flexible diaphragms, nor did they take into account the required plunger or piston structure necessary to facilitate such manufacturing procedures and to improve the attachment and rolling performance of such diaphragms.